The most under rated waster of strokes in golf. Old, worn, dirty, slippery grips.
I see golf bags full of squeaky clean club faces, that are meticulous cleaned groove by groove and protected by custom made wood and iron covers with battery operated heaters, that cost more than the clubs.
The head cover is removed, the club is removed from the bag and I see a grip that has been on the club since it came from the factory, when there was still an East and West Germany, with grooves worn in where the thumbs depress and slippery with hand oils and dirt.
Wanna save some strokes? After each round or before each round, take a wet towel and rub down your grips thoroughly. Then take the dry end of the towel and dry them thoroughly. You will see some nasty black grime on your towel and you may have to repeat this process several times. If they are still slippery, replace them.
I just saved a good many of you about 5-10 strokes. Slippery dirty, or old grips give you the feeling you have to death grip the club in order for it not to go flying out of your hands. That counts as excess tension and ruins more things than I can list.